Yes, it is different. Even though Aveling & Porter is always a good guess -- they had a 2/3 market share in Road Rollers -- this one is a mid to late 1920s Ruston & Hornsby, quite similar to this one:
which is a 10 ton 6 n.h.p. Roller from 1928.

... You are also right about checking details as most of these machines were very similar.

I wasn't addressing you, Wrenchhead, as I know you care for details.
With these steam engines it is just like with, let's say, US cars from the seventies: for the untrained eye they all look the same. I find steam engines fascinating. If there is a steam gathering near you by all means visit it ... you will not regret it!